In recent years, for imaging optical systems such as video cameras and digital still cameras, demands for high zoom ratio, high performance over an total zoom range, and compactness have become strong. As a zoom lens for meeting these demands, a zoom lens comprising, arranged in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, that varies power by moving each lens group, has been provided (for instance, refer to Patent Document 1).